The present invention relates to an apparatus and method for supportably positioning an implantable hearing aid actuator within a patient""s skull, and more particularly, to a positioning apparatus and method that provides ease-of-installation, range-of-application, actuator loading and depth positioning advantages.
Several types of implantable hearing aid devices have been proposed. Principally, such devices include those which utilize implanted electromechanical transducers for stimulation of the ossicular chain and/or oval window (see e.g., U.S. Pat. No. 5,702,342), and those which utilize implanted excitor coils to electromagnetically stimulate magnets affixed within the middle ear (see e.g., U.S. Pat. No. 5,897,486). For purposes hereof, such electromechanical transducers and excitor coils, as well other implanted devices that stimulate the ossicular chain and/or oval window will be collectively referred to as xe2x80x9cimplantable hearing aid actuatorsxe2x80x9d.
In most instances, hearing aid devices of the above-noted nature entail supportable positioning of the given implantable actuator within a patient""s skull. In many procedures, an opening is surgically defined in a patients skull and the implantable actuator is inserted through the opening for supportable positioning within the mastoid process. In conjunction with such implant procedures, precise placement and orientation of the implantable actuator can be of paramount importance to achieve best results.
To yield precise positioning a number of arrangements have been proposed, wherein implantable actuator(s) may supportably disposed for selective in-site positioning in multiple dimensions relative to a skull mounting device. While such arrangements have represented an advance in the art, they often entailed the positioning of a number of separate, hard-to-handle components, thereby adding to the complexity already associated with implant procedures. Additionally, the present inventors believe that further enhanced positioning of implantable actuators is achievable, particularly with respect to the depth profile which can vary significantly from patient to patient.
In view of the foregoing, a primary objective of the present invention is to provide an apparatus and method for supportably positioning an implantable hearing actuator at a desired location with enhanced ease-of-installation. Additional objectives are to provide an implantation apparatus and method that yields enhanced accuracy in implantable hearing aid actuator positioning and/or range-of-application advantages. Yet a further objective of the present invention is to provide an apparatus and method that facilitates accurate, contact loading of an electromechanical transducer relative to a patient""s ossicle.
One or more of the above-noted objectives as well as additional advantages are provided in the inventive apparatus which includes a carrier device for carrying an implantable hearing aid actuator at a first end, and a swivel device for pivotably supporting the carrier device. Such pivotable support allows the first-end of the carrier device to be laterally pivotable in first and second dimensions relative to the swivel device. The apparatus further includes a mounting device for mounting the apparatus to a patient""s skull, wherein the swivel device may be secured to the mounting device.
In one aspect of the present invention the swivel device is provided in a unitary fashion. That is, the swivel device is selectively positionable relative to and otherwise securable to the mounting device as a single unit. Such an arrangement simplifies installation procedures in conjunction with hearing aid implants. Further, to enhance actuator depth positioning, the carrier device and swivel device are preferably adapted to allow the carrier device to be selectively positioned in a third dimension relative to the swivel device.
Preferably, the unitary swivel device includes interconnected, opposing first and second holder members with a pivot member (e.g., a rotatable ball) captured between the first and second holder members. The pivot member may include an opening for supportably receiving the carrier device, wherein the carrier device is slidably positionable in the opening along a linear continuum of positions in the third dimension. As may be appreciated, pivotable movement of the carrier device will effect corresponding rotation of the pivot member relative to the interconnected first and second holder members.
In the later regard, the first and second holder members may be interconnected to permit a limited range of relative movement therebetween, thereby facilitating selective rotation of the pivot member upon pivotable movement of the carrier device. Relatedly, the inventive apparatus may further comprise a locking member interconnectable to the mounting device to selectively apply a compressive force to and thereby restrict relative movement between the first and second holder members, wherein a selected angular orientation between the carrier device and the mounting device may be maintained by the locking member.
Further, the locking member may also be employable to lock-in a selected linear position of the carrier device relative to the swivel device. More particularly, the pivot member may include a plurality of slits extending through an upper portion thereof to define a plurality of separated, upper portions of the pivot member. Correspondingly, the first holder member may comprise an aperture sized for contact positioning about the slitted portion of the pivot member. Consequently, when the locking member is interconnected to the mounting device to apply a compressive force to the first and second holders, such force will effect inward movement of the plurality of separated, upper portions to restrictably engage the carrier device.
In another aspect of the present invention, the carrier device may be interconnected to the swivel device in a manner that allows for selective advancement of the carrier device relative to the swivel device, wherein a first degree of actuator depth positioning latitude is provided; and, the carrier device may comprise at least a first carrier member and an interconnected second carrier member having a distal end connectable to an actuator, wherein the second carrier member is selectively advancable relative to the first carrier member to yield a second degree of depth positioning latitude. Such multiple depth positioning functionality not only facilitates accurate placement of an implantable hearing aid actuator but also facilitates a greater depth positioning range for an increased range of patient applications. In one arrangement, the first and second carrier members may be disposed coaxially and interconnected for selective, telescoping advancement of the second carrier member relative to the first carrier member.
Preferably, the first and second carrier members may be threadably interconnected, wherein driven rotation of the first carrier member effects a predetermined degree of linear travel by the second carrier member. In this regard, the swivel device may include an opening for supportably receiving the carrier device, wherein a top end of the first carrier member projects from the swivel device to provide ready access for driven rotation by an accessory tool.
In addition to first and second carrier members, the carrier device may further include a third carrier member, rotatably interconnected to the first carrier member, for restricting rotational movement of the second carrier member. In one arrangement, the second carrier member may include a linear slot while the third carrier member includes a projecting retention pin positioned within the slot of the second carrier member. As such, when the third carrier member is rotationally fixes (e.g., via use of a locking member as noted above) and the first carrier member is rotated, the third carrier member restricts rotation of the second carrier member, thereby causing the second carrier member to telescope away from both of the first and third carrier members.
In one embodiment, a mounting device is provided which includes a cylindrical barrel portion for supportably receiving a swivel device and carrier device interconnected thereto. The barrel portion includes a bottom end plate and is internally threaded, wherein the swivel device may be xe2x80x9clocked-inxe2x80x9d between an externally threaded locking member and the bottom end plate. The swivel device may include interconnected, top and bottom plate members with opposing central apertures having beveled edge surfaces for receiving a round pivot member therebetween. The pivot member is provided with a central opening therethrough for slidably receiving an outer support member of the carrier device. The carrier device further includes an internal shaft member rotatably interconnected at a top end to a top end of the outer support member, and interconnected at a bottom end to a telescoping member. In turn, a distal end of the telescoping member is interconnected to an electromechanical transducer actuator.
The entire carrier device may be selectively located at one of a linear continuum of positions relative to the swivel device to provide a first measure of depth positioning control. Further, the carrier device may be pivoted relative to the mounting device to provide for lateral positioning of the electromechanical transducer actuator. When a desired depth and angular orientation of the carrier device is established, such position may be xe2x80x9clocked-inxe2x80x9d by tightening the locking ring down on the swivel assembly. Then, the telescoping member of the carrier device may be selectively advanced to position the electromechanical transducer actuator in a desired contact position with the ossicular chain (e.g., contact with the incus bone) or oval window.
In view of the foregoing, it will apparent that an inventive method for positioning an implantable hearing aid actuator is also provided. The inventive method includes the steps of attaching a mounting device to a patient""s skull and supporting a swivel device on the mounting device, wherein the swivel device pivotably supports a carrier device having an implantable hearing aid actuator interconnected thereto. The method further provides for the positioning of the carrier device so as to locate the implantable hearing aid actuator at a desired location within the patient""s skull.
Preferably, the supporting step is achieved via the placement of the swivel device as a single unit into a support position on the mounting device. In one embodiment, this may be achieved by inserting the swivel device as a unit into a barrel portion of the mounting device and supportably engaging a bottom end plate of the barrel portion.
The positioning step of the inventive method preferably includes the sub-steps of pivoting the carrier device and interconnected implantable hearing aid actuator into a desired angular orientation relative to the mounting device within a patient""s skull, and advancing the carrier device relative to the swivel device. Further, in an arrangement where the carrier device includes at least first and second carrier members, the positioning step may further include the sub-step of advancing the second carrier member relative to the first carrier member.
When an electromechanical transducer actuator is utilized, a desired contact location may be defined on the ossicular chain (e.g., the incus bone) or oval window within a patient""s skull, wherein a probe tip of the electromechanical transducer actuator is brought into gradual contact with the contact location during positioning. In this regard, the inventive method may further provide for advancing the second carrier member relative to the first carrier member so as to provide a predetermined degree of loading by the probe tip on the contact location.
Numerous additional aspects and advantages of the present invention will become apparent to those skilled in the art upon consideration of further description that follows.